Device for repeating alternating-current telegraph signals by means of vacuum tubes



. June 16, 1925. 1,542,546

J. P. FERRITER ET AL, DEVICE FOR REFEATING ALTERNATING CURRENT TELEGRAPHSIGNALS BY MEANS OF VACUUM TUBES Filed Aug. 29, 1923 '2 Sheets-Sheet lgwwnto'as Wi @W V m June 16, 1925. 1,542,546

DEVICE FOR REPEATING ALTERNATING CURRENT TELEGRAPH SIGNALS J. P.FERRITER ET AL BY MEANS OF VACUUM TUBES Filed g. 29. 19215 2Sheets-Sheet 2 Patented June 16, 1925.

UNITED STATES PATENT or cs.

JOHN P. FERBI'IER, OF OCEANPORT, AND WRIGHT JOHNSON, OI REID BANK,

NEW JERSEY.

DEVICE FOB-BEPEATING AIiTERNATTNG-CURRENTTELEGRAPH SIGNALS BY MEANS OFVACUUM TUBES.

Application filed August 29, 1928. Serial No. 660,023.

To. all whom it may 00mm:

Be it known that we, JOHN P. FERRITER and WRIGHT H. JOHNSON, citizens ofthe United States, residing, respectively, at Oceanport and Red Bank, inthe county of Monmouth and State of New Jersey, have invented certainnew and useful Improvements in Devices for Repeating Alternating-Gurrent Telegraph Signals y Means of Vacuum Tubes, of which thefollowing is a specification.

This invention relates to vacuum tube repeaters and more especially suchas are employed in line telegraphcircuits.

The present types of telegraph repeaters in use are not satisfactory dueto mechanical reasons and to repeater lag which causes attenuation ofsignals. If several setsof repeaters are used, false signals result. Upto the present time vacuum tube repeaters have been impracticable due tothe fact that direct current has largely been used for line current. Byusing alternating line current, the use of tube repeaters is possibleand profitable. False signals and other repeater troubles are therebyeliminated.

In order to more clearly disclose the nature of our invention thefollowing figures'of the drawing are attached and in which:

Figure 1 represents an arrangement for two-tube two-wayrepeaters. V

Figure 2 represents a two-way four-tube re eater system.

eferring more particularly to the drawings, Figure 1 shows an ironcoretransformer Mhaving the primary windings O and O and the secondarywindings, P, and P. A similar transformer m is also provided. N and nare iron] core transformers provided with suitable windings. Tubes 1 and2 are three-electrode vacuum tubes lighted by a battery-A. The platepotential for the tubes is furnished by batteries B and b. The grids ofthe tubes are properly biased for correct operation by means ofbatteries C and 0. AL and dare artificial line rheostats and condensersfor the purpose of balancing the repeaters.

The artificial line rheostats and condensers AL are adjusted until acurrent introduced into the middle point of windings O and O of thetransformer.M by means of the transformer N divides equally through 0 toline and O to artificial line. This is similar to balancing an ordinaryduplex. A similar balance must be obtained for all so that currentsupplied by the transformer 71. divides equally through p and p to theartificial line. Thus P, and P are balanced against outgoing currentfurnished by transformer N and a similar condition obtains for p and pand n.

Suppose that an alternating current, the half-waves of which have theiramplitudes modified according to any predetermined signalling flow,comes in over the line alternating current through 0 and through 0 andAL in parallel with the secondary of N to the ground. There is then anunbalance of current in 0 and 0 An alternating electro-motive force willthen be induced across the windings P and P in series and impressed onthe grid of the tube 1. A large alternating vibration takes place in theplate ing go is similar to that described above.

gure 2 shows a repeater using four tubes. The objectof this system is todivide the voltage across windings P and P (7) and p between two gridsso that approximately one-half the voltage is placed upon the grid as isthe case when single tubes are used. This allows the tubes to be workedto better advanta e and prevents distortion. The system of balancing isthe. same as described above.

Suppose that a signal impressed on M at a given instant makes the gridof tube 1 positive and the grid of tube 2 negative. The plate current oftube 1 will increase through S and the plate current of tube 2 willdecrease through S A voltage will be induced in 1 and p in series. Atthe next half cycle t e grid of tube 1 becomes negative and the grid oftube 2. becomes positive so that the plate current of tube 1- of tube 2increases through S The action of tubes 3 and 4 is similar to that abovedescribed.

Having thus described our invention, we claim:

In combination with a vacuum "tube du-' plex amplifier, an alternatingcurrent telegraph line, a plurality of pairs of threeelectrode' vacuumtube detectors, each tube of said pairs having its filament in serieswith that of another, each pair having an iron core transformer ofprimary and secondary windings, said primary being connected to saidline and to the grid of one tube, said secondary being connected to anartificial lineand to the grid of the other tube, an-

other transformer having its primary and secondary windings connected tothe plates said second mentioned transformer, for the.

purpose of providing means for impressing a substantially sustainedsignalling alternat.

ing current the half-waves of which have their amplitudes modifiedaccording to any predetermined signalling fiow.-

In testimony whereof we aflix our signatures.

JOHN P. FERRITER.

WRIGHT H. JOHNSON.

